British scientists have made a landmark discovery that could help slow or even stop the spread of prostate cancer to the bones.

Once prostate cancer has formed tumour outposts in bone marrow, the disease is usually considered incurable.

But scientists at York University have discovered why prostate cancer so often spreads to the bone – and how the process can be stopped.

They found that a protein in bone marrow acts like a ‘magnetic docking station’ for prostate cancer cells in the blood.

And they have also discovered that a non-toxic drug known only as AS1517499, previously tested for treating allergic asthma, appears to stop the cancer from growing once embedded in the bone.

The researchers now hope to test the drug on patients with advanced prostate cancer.

Professor Norman Maitland, chairman of molecular biology at York University, said circulating prostate cancer cells were like space ships searching for places to dock in the body to start a new colony.

“Without this docking station, the “ship”, or cell, will just float around, not causing any further harm,” he added.

Certain proteins in bone act like ‘magnetic docking stations for the receptors on the stem cells of the cancer’. Once ‘docked’, a signal is sent to the cancer cell’s nucleus, which instructs it to start growing the cancer colony.

As a result, about 80 per cent of men with advanced prostate cancer suffer from tumours in the bone. These grow and eventually overcome the body, proving fatal.

Maitland said clinical trials of AS1517499 were ‘some way off’ and that, when they did start, they would almost certainly involve men in the advanced stages of the illness.

Meanwhile, the asthma medication Singulair (montelukast) appears linked to neuropsychiatric side effects, such as depression, aggression, nightmares and headaches, according to a new review by Dutch researchers.

The study’s findings were published September 20 in Pharmacology Research and Perspectives.

But experts are not yet ready to pull the plug on this class of medication.

“In our study, we give prescribing physicians the advice to be alert for signs and symptoms for allergic granulomatous angiitis [a rare complication associated with the drug] and for severe neuropsychiatric symptoms,” said study lead author Dr. Meindina Haarman.

“The doctor still decides whether or not to treat the patients with montelukast,” said Haarman, from University Medical Center Groningen in the Netherlands.

Dr. Matthew Lorber is a psychiatrist at Lenox Hill Hospital in New York City. He cautioned against discontinuing the medication in children with asthma, a lung disease that inflames and narrows the airways.

“Ultimately, asthma can be a life-threatening condition in children and cannot be ignored, so I do recommend to parents that their children continue with these lifesaving medications,” Lorber said.

“It is just very important to monitor for these risks, and it is vital that doctors warn parents about these risks before their children start these medications so they know what to be on the lookout for,” Lorber added.

Singulair is an asthma and allergy medication, available as a pill or as dissolvable granules, taken once daily. It’s part of a class of drugs called selective leukotriene receptor antagonists, according to Haarman. Other medications in this class include zafirlukast (Accolate) and zileuton (Zyflo and Zyflo CR).

Since 2009, the United States Food and Drug Administration (FDA) has required these drugs to carry a warning that they are associated with neuropsychiatric side effects, such as agitation, aggression, anxiousness, dream abnormalities and hallucinations, depression and insomnia. Suicidal thinking and behavior (including suicide), and tremor are also possible side effects.

The current study used two databases to see how prevalent these types of side effects were in children and adults taking Singulair. One was the Netherlands Pharmacovigilance Center Lareb, which reported more than 300 adverse side effects after taking Singulair.

The second was a global database called VigiBase, maintained by the World Health Organization to monitor adverse side effects from medications. This database, which includes more than 120 countries, contained almost 18,000 reports of adverse events after taking Singulair.

The odds of depression were nearly seven times higher in kids and adults taking Singulair. The odds of aggressive behavior were 30 times higher in children taking the drug, researchers found.

The odds of thinking about suicide were 20 times higher and the odds of nightmares were more than 22 times higher in adults and kids taking the drug, with children especially prone to nightmares, the study showed. The risk of headaches was twice as high in people taking Singulair.

The study authors acknowledge it is hard to tease out a cause-and-effect relationship. For example, having asthma has been linked to a higher risk of depression, so is the effect from the disease or the treatment?